With continuous advancement of mobile terminal technologies, users now demand for more and more functions of mobile terminals.
Take Subscriber Identity Module (SIM) cards as an example. For the SMI cards currently available, communication operators generally have an absolute control over mobile phones they purchased. Therefore, the operators usually adopt the SIMLock technology to restrict users from using SIM cards of other operators in the mobile phones. For example, mobile phones customized for China Unicom do not allow for use of SIM cards of China Mobile Communication Corporation therein.
In terms of physical hardware, a primary SIM card slot and a secondary SIM card slot are defined in each mobile terminal. The mobile terminal operates normally, only when an SIM card complying with the SIMLock specification is inserted in the primary SIM card slot. When no primary SIM card complying with the specification is inserted in the primary SIM card slot, the mobile terminal will be locked out even if an SIM card complying with the specification is inserted in the secondary SIM card slot.
The SIMLock technology is implemented on the basis of a white list of operators which is built in the mobile terminal, i.e., a list of Mobile Country codes (MCCs) and Mobile Network Codes (MNCs) recognized and specified by the operator. The MCC resource is allocated and managed uniformly by the International Telecommunication Union (ITU) to uniquely identify a country to which a mobile subscriber belongs, and an MCC code has three bits (“460” for China). An MNC code has two bits and is used to identify a network to which the mobile subscriber belongs. For SIM cards which are not listed in the white list, functions will be restricted: for example, dialing a phone number and sending a short message are forbidden, or even the mobile phone is locked out directly.
Although the dual-card-dual-standby and multi-card-multi-standby technologies have appeared, there still lacks a thorough understanding by the operators on how to effectively utilize such technologies. Currently, practices of controlling functions within a mobile phone are all based on the SIMLock specification of the standard 3GPP/3GPP2 (3rd Generation Partnership Project 2), and all resources of a mobile phone are treated uniformly: either all functions are allowed to be used by the user or only an emergency call can be made.
Obviously, it is impossible for the user to dial a phone number or send a short message through use of the telephone directory on the secondary SIM card when the secondary SIM card is locked out. This greatly restricts the use of the mobile phone and represents great inconveniences to the user.